Various types of conventional support cushions have been introduced or proposed for providing a reduced pressure on the body and/or for providing a desired pressure distribution.
Such cushions are typically intended for use by partially or completely immobilized patients who maintain a substantially stationary position for long periods of time. Cushions have been specifically designed for use as seating cushion or back support cushion for a patient when seated in a chair, especially a wheelchair. A variety of these designs are in use or have been proposed which are intended to overcome some of the problems encountered by the patient.
For example, when a person is sitting on a cushion, the person's weight is concentrated to a great extent in the buttock area, and the pressure tends to be greatest in the ischial, trochanter and sacral areas. Excessive pressure on these areas for prolonged periods of time can result in restricted circulation of blood and in tissue necrosis with the resultant formation of pressure sores or decubitis ulcers.
Another problem that must be addressed by an effective cushion design is the stability of the body when placed on or against the cushion. This is especially important with a seat cushion. To the extent that a patient may tilt, lean, or otherwise actually shift position on the cushion, there is a danger that the response of the cushion may be inconsistent with the maintenance of the desired stability. For example, a cushion containing a fluid may not provide sufficient resilience or resistance to movement.
Some cushions contain relatively large amounts of liquid, and this can make the cushion relatively heavy and difficult to handle, especially for elderly, infirm, or disabled persons.
With almost any cushion design, cost considerations are important. A cushion having a complex design may be difficult to manufacture, and may therefore be too costly to be of practical use.
In view of the above-discussed problems, it would be desirable to provide a cushion with improved features and support characteristics and which could still be relatively inexpensively manufactured.
It would be beneficial if such an improved cushion would provide sufficiently low pressures on the body so that the body could be comfortably supported by the cushion with a minimal, or at least reduced, tendency to cause tissue stress and resultant pressure sores.
It would be advantageous if such an improved cushion could be used in a way that would permit the cushion to readily and effectively conform substantially to the contour of the body portion engaged with the cushion.
In addition, it would be desirable to provide an improved cushion which could support a body or portion thereof in a relatively stable manner while still being capable of accommodating the movement or repositioning of the body.
It would also be beneficial if the design of the improved cushion could accommodate fabrication from relatively light weight components so that the overall weight of the cushion is not excessive.